A. Sm和Nd同属稀土元素,能最大程度保持体系的封闭性 B. 对变质作用敏感,能确定变质年龄 C. 能测定海相碳酸盐岩年龄 D. 测定硅酸盐年龄
A. in high latitudes B. near the equator C. on north or south headings D. on intercardinal heading